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#!/usr/bin/perl
use warnings;
use strict;
sub squarefree_integers {
my ($max) = @_;
my @primes = (2 .. sqrt $max);
for (my $i = 0; $i <= $#primes; ++$i) {
@primes = grep $_ <= $primes[$i] || 0 != $_ % $primes[$i], @primes;
}
my @sfi;
INTEGER:
for my $n (1 .. $max) {
0 == $n % ($_ * $_) and next INTEGER for @primes;
push @sfi, $n;
}
return @sfi
}
use Test2::V0;
plan 2;
is [squarefree_integers(113)],
[1, 2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 26, 29,
30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 46, 47, 51, 53, 55,
57, 58, 59, 61, 62, 65, 66, 67, 69, 70, 71, 73, 74, 77, 78, 79,
82, 83, 85, 86, 87, 89, 91, 93, 94, 95, 97, 101, 102, 103, 105,
106, 107, 109, 110, 111, 113],
'A005117';
=head1 List generated by
#! /bin/bash
for n in {1..500} ; do
factor $n
done | grep -vE ' ([0-9]+) \1( |$)' | cut -d: -f1
=cut
is [squarefree_integers(500)],
[1, 2, 3, 5, 6, 7, 10, 11, 13, 14, 15, 17, 19, 21, 22, 23, 26, 29,
30, 31, 33, 34, 35, 37, 38, 39, 41, 42, 43, 46, 47, 51, 53, 55,
57, 58, 59, 61, 62, 65, 66, 67, 69, 70, 71, 73, 74, 77, 78, 79,
82, 83, 85, 86, 87, 89, 91, 93, 94, 95, 97, 101, 102, 103, 105,
106, 107, 109, 110, 111, 113, 114, 115, 118, 119, 122, 123, 127,
129, 130, 131, 133, 134, 137, 138, 139, 141, 142, 143, 145, 146,
149, 151, 154, 155, 157, 158, 159, 161, 163, 165, 166, 167, 170,
173, 174, 177, 178, 179, 181, 182, 183, 185, 186, 187, 190, 191,
193, 194, 195, 197, 199, 201, 202, 203, 205, 206, 209, 210, 211,
213, 214, 215, 217, 218, 219, 221, 222, 223, 226, 227, 229, 230,
231, 233, 235, 237, 238, 239, 241, 246, 247, 249, 251, 253, 254,
255, 257, 258, 259, 262, 263, 265, 266, 267, 269, 271, 273, 274,
277, 278, 281, 282, 283, 285, 286, 287, 290, 291, 293, 295, 298,
299, 301, 302, 303, 305, 307, 309, 310, 311, 313, 314, 317, 318,
319, 321, 322, 323, 326, 327, 329, 330, 331, 334, 335, 337, 339,
341, 345, 346, 347, 349, 353, 354, 355, 357, 358, 359, 362, 365,
366, 367, 370, 371, 373, 374, 377, 379, 381, 382, 383, 385, 386,
389, 390, 391, 393, 394, 395, 397, 398, 399, 401, 402, 403, 406,
407, 409, 410, 411, 413, 415, 417, 418, 419, 421, 422, 426, 427,
429, 430, 431, 433, 434, 435, 437, 438, 439, 442, 443, 445, 446,
447, 449, 451, 453, 454, 455, 457, 458, 461, 462, 463, 465, 466,
467, 469, 470, 471, 473, 474, 478, 479, 481, 482, 483, 485, 487,
489, 491, 493, 494, 497, 498, 499],
'Up to 500';
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